Important information that is kept in real memory might be written periodically to the paging file. This helps devices handle multitasking functions. A malicious user who has physical access to a server that has been shut down can view the contents of the paging file. The attacker can move the system volume into a different computer and then analyze the contents of the paging file. This is a time-consuming process, but it can expose data that is cached from RAM to the paging file.
IMPORTANT NOTE: Clearing the page file will secure delete information on the temporary page file. This process takes time depending on page file size and drive speed. On a very large memory server with slow disk access, could take 20 to 30 minutes. This only affects a planned server shutdown, it won't process on a "not planned" shutdown or emergency shutdown.
More Info: https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/shutdown-clear-virtual-memory-pagefile